Merge branch 'cc/apply-am'

"git am" has been taught to make an internal call to "git apply"'s innards without spawning the latter as a separate process. * cc/apply-am: (41 commits) builtin/am: use apply API in run_apply() apply: learn to use a different index file apply: pass apply state to build_fake_ancestor() apply: refactor `git apply` option parsing apply: change error_routine when silent usage: add get_error_routine() and get_warn_routine() usage: add set_warn_routine() apply: don't print on stdout in verbosity_silent mode apply: make it possible to silently apply apply: use error_errno() where possible apply: make some parsing functions static again apply: move libified code from builtin/apply.c to apply.{c,h} apply: rename and move opt constants to apply.h builtin/apply: rename option parsing functions builtin/apply: make create_one_file() return -1 on error builtin/apply: make try_create_file() return -1 on error builtin/apply: make write_out_results() return -1 on error builtin/apply: make write_out_one_result() return -1 on error builtin/apply: make create_file() return -1 on error builtin/apply: make add_index_file() return -1 on error ...